For example, a certain type of contact combustion-type gas sensor used to detect a flammable gas is configured to include a gas detection element with a gas sensitive part firmly fixed to the surface of a temperature-measuring resistor that generates heat when energized, where the gas sensitive part is formed by an oxidation catalyst carried on a carrier made of metal oxide sintered compact.
In such a contact combustion-type gas sensor, when a silicone compound or a poisonous substance such as hexamethyldisiloxane or silicone oil exists in the atmosphere of a space to be measured, the poisonous substance is adsorbed and accumulated on the surface of the oxidation catalyst (poisoning). This causes the performance (reactivity) of the oxidation catalyst to deteriorate and the detection sensitivity to gradually degrade.
In view of such a problem, for example, it is conceivable to dispose a silicone removal filter and thereby prevent the poisoning of the gas detection element. A gas sensor that is provided with such a silicone removal filter is disclosed, for example, in Patent Literature 1.